Duplicator for machine tools



March 27, 1945. c. JOHNSON DUPLICATOR FOR MACHINE TOOLS Filed March 20, 1941 13 Sheets-Sheet l Snnentor CLARENCE JOHNSON March 27, 1945. c. JOHNSON I 72 4 DUPLICATOR FOR MACHINE TOOLS Filed March 20,194; '15 SheetS Sheet 2 Jnmmtor CLARENCE JOHNSON 3 I L9. v

March 27, 1945. c. JOHNSON nurmcnon FOR MACHINE TOOLS FiiedMarch 20, 1941 13 Sheets-Sheet 3 FIG. '3

Jmqentor CLARENCE JOHNSON FIG. 5

(Inorneg March 27, 1945. -c. JOHNSON 2,372,426

I nurmcmon FOR momma TOOLS Filed March 20, 1941 13Sheets-Sheet 4 FIG. 8

3uuntor FIG. 7 CLARENCE JOHNSON March 27, 1945. c, JQ Q 2,372,426

DUPLICA'I'OR FOR MACHINE TOOLS Filed March 20, 1941 15 Sheets-Sheet 5 I 3m entor CLARENCE JOHNSON FIG. 9 W W/9M -March 27, 1945. c. JOHNSON ,7 ,3

' DUPLICATOR FOR MACHINE TOOLS I i iled March 20, 1941 t 13 sneets sh'et 6 FIG. 10

3nnentor CLARENCE JOHNSON Mai-ch 27, 1945.

Filed March 20, 1941 C. JOHNSON DUPLICATOR FOR MACHINE TOOLS 13 Sheets-Sheet 7 SUPPLY FIG. ll

, 3npe ntor CLARENCE JOHNSON March 27,- 1945. c. JOHNSON 2,372,426

DUPLICATOR FOR MACHINE TOOLS Filed March 20, 19 41 13 Sheets-Sheet 9 AIR SUPPLY FIG. 29

Z'mventor CLARENCE JOHNSON FIG. I4-

March27, 1945. 2 QJOHNSON; 2,372,426

DUPLICATOR FOR MACHINE TOOLS Filed March 20, 1941. 13 Sheets-Sheet 10 FIG. I5

use no 5 v Q K FIG. l6

30s \1 f IU so?s\ $305 321 3o? an 3l0 320 FIG. 28 I :l 3maentor CLARENCE JOHNSON Marh 27, 1945. c. JOHNSON DUPLICATOR FOR MACHINE TOOLS Filed March 20, 1941. 13 Sheets-Sheet 11 3 m m Y 2 m ,m .NN mum .uu 0 3 W a n- N. m 5 0 w E 08 m 7 3n 2 M 08 3, u C

o6 own N3 mom m3 OON mom

5m hmm mmn mmm wON wmmm

- March 27, 1945. c. JOHNSON 3 2,372,426

I DUPLICATOR FOR MACHINE TOOLS 1s Sheets-Shet 12 Filed March 20, 1941 3nventor CLARENCE JOHNSON C(ttomeg March 27, 1945. C.JO HNSON DUPLICATOR FOR MACHINE TOOLS 13 Sheets-Sheet 15 Filed March 20, 1941 FIG. 24

3nnentor FIG. 25

CLARENCE JOHNSON attorney FIG. 26

. sinking machines and the Patented Mar. 27 1945 Clarence Johnson,

South Euclid, Ohio, assign to Bailey Meter Company, a corporation of Delaware Application March 20, 1941, Serial No. 384,375

21 Claims.

This invention relates to duplicators for. controlling the operation of a machine tool so that it forms a work piece to a contour or configuration determined by a template, pattern, or cam.

One of the objects of my invention is toimprove the sensitivity of duplicators of the type described, and thereby increase the accuracy with which the work piece is formed.

A further object of my invention is to provide a duplicator of materially simpler construction. than those now available.

A further object of my invention is to provide a duplicator employing no moving parts in the feeler mechanism scanning the template, pattern or cam.

In accordance with my invention the template, pattern or cam for producing the desired configuration f the work piece is scanned by a jet of fluid issuing from a nozzle, so that variations in the shape of the template, pattern or cam cause corresponding changes in the rate at which fluid is discharged from the nozzle, which changes in turn control the relative movement of the tool ample power is available for accurately positioning the tool relative to the work piece.

Further, in accordance with my invention the relative rates of movement between the tool and work piece in two directions are simultaneously controlled, so that the rate of feed of.the tool remains substantially constant regardless of changes in contour of the template, pattern or cam.

Further, in accordance with my invention separate and independent means are provided for controlling the rate of relative movement between tool and work piece in each direction.

Obviously, a duplicator of the type forming the subject matter of my inventionmay be employed with machine tools of various types, such as milling machines. lathes, slotters, planers, die- I' e in which the relaand work may be suitexample I will illustive teed between the tool ably controlled. Byway of fluid is discharged trate and describe my invention as applied to a few specific types of machine tools. Further applications and modifications of my invention will be readily apparent.

In the drawings:

Fig. 1 is a side elevation and Fig. 2 is a front elevation of a vertical milling machine illustrating the application of my invention thereto.

Fig. 3 is a sectional view taken along the line 3-3 of Figs. 1 and 2 in the direction of the arrows.

Fig. 4 illustrates a modified form of nozzle scanning mechanism.

Fig. 5 is a cross-sectional view of a pilot valve for controlling the flow of fluid to and from a hydraulic servo-motor for regulating the relative feed of the tool and work piece.

Fig. 6 illustrates diagrammatically a modified form of fluid'pressure system.

Fig. 7 is a side elevation and Fig; 8 is a plan view of an engine lathe showing the application of my invention thereto.

Fig. 9 illustrates a further embodiment of my I invention incorporating a modification.

Fig. 10 is a plan view of an engine'lathe illus- Ztrating'the application of a modified form of my invention thereto. a Fig. 11 illustrates diagrammatically the various circuits employed in the embodiment of my.

Q invention shown in Fig. 10.

' Fig. 12 is a side elevation of a hydraulic power unit.

Fig. 13 is a fragmentary view line Iii-I3 of Fig. 12.

.Fig. 14 is an elevation which may be employed in in Fig. 12.

Figs. 15 and 16 are fragmentary views illustrate ing modifications of certain parts of the power unit shown in Fig. 12.

Fig. 17 is a cross-sectional view of one form of pilot valve employed in the power unit illustrated in Fig. 12.

' Fig. 18 is an elevation view of a sleeve element taken along the view of a fluid pump the power unit shown of the pilot valve shown in Fig. 17.

Fig. 19 is an end view of a bearing element 0! the pilot valve shown in Fig. 1'7.

Fig. 20 is an elevation view and Fig. 21 a crosssection view. of another form of pilot valve which may be incorporated in the powerunit shown in Fig. 12 when used for certain purposes.

Fig. 22 illustrates to larger'size and in greater detail the tracer mechanism shown in Fig. 10.

Fig. 23 illustrates a modified Figs. 24 and 25 are elevation and plan views respectively of another form of tracer mechanism.

Fig. 26 illustrates a further modified form of tracer mechanism.

Fig. 27 is a plan view of the modified form of my invention shown in Fig. 10 applied to a milling machine as shown in Figs. 1 and 2.

Fig. 28 is a diagrammatic view of the circuits employed in the embodiment of my invention shown in Fig. 27.

Fig. 29 illustrates an alternate arrangement of tracer and nozzle mechanism which may be incorporated in the various embodiments of my invention.

Referring now to Figs. 1, 2 and 3, I therein show a vertical milling machine having a column I a work table 2, and a rotatable form milling cutter 3. The work table 2 is carried in a saddle 4 mounted on horizontal a knee 6 which is supported in vertical guide ways 1 formed on the column I. A micrometer hand wheel 8 is provided for positioning the saddle 4 along the guide ways 5. -A similar hand wheel 2 is provided for positioning the knee 6 along the vertical guide ways I. The work table 2 is mounted on a horizontal guideway l formed in the saddle 4 and is positionable relative thereto by a lead screw H. The cutter 3 is secured to a spindle l2 rotated by a motor I 3, which may be further adapted to position the work table 2 along one or more'of the gui eways as well known.

At' I4, is shown atypical work piece consisting of a concave forging of more or less elliptical shape and in rough form having a raised blank face extending around its entire periphery. The

machining operation I have chosen to illustrate my invention as controlling consists in forming a male flange face on this outer face. The cutter 3 is suitably shaped to relieve the outer edge of the flange, and by my invention the work piece is automatically moved relative to the cutter so that the latter accurately forms the outer profile of the raised portion of the flange.

The work piece i4 is shown as being secured to a fixture l by adjustable clamping means it.

Because of the nature'or the machining operation to be performed the fixture I5 is mounted on a circular table 11. secured to the work table 2 and rotatable at desired speed by the motor l2 through suitable reducing gears and shafting (not shown). The machining of the work piece i4 is completed in one revolution of the circular table II, during the revolution the work piece being moved relative to the cutter 3 to accurately profile the male flange by means nowv to be described.

The fixture II has a. horizontally extending skirt II forming'a cam or template, the contour of which is formed to produce the desired contour of the raised portion of the flange on the workpiece l4.- A raised barrier is preferably employed to hold chips cut from the work piece from scattering.

Fastened to the column i is an arm 2| in which is Journaled a nozzle 22. Secured to the nozzle is an extension 23 follower 24 having a projection 25 urged against the cam or template I! by a spring 28. The nozzle 22 is-preierably resiliently joumaled in the arm 2| by means of spaced collars 21 and spring guide ways I carried by' which pivotally supports a l discharged from the as shown-in Fig. 3, the rate of of that of the template l9.

' spond" implies that the 28, which provide for. lateral movements, thereby preventing injury to the nozzle in the event that the follower 24 is inadvertently jammed against inserted an orifice or other partial restriction 30. jet of fluid is continuously Normally therefore a port 21 against the follower 24, which acts as a valve member for the port, its movements toward and away from the port governing the rate of discharge of fluid therefrom. That is to say. when the follower 24 is positioned to the left, or closer to the port 3|, discharge from the port is decreased, whereas when the follower 24 is positioned to the right, or away from the port, the'rate of discharge from the nozzle increases. Such ehanges in the rate of discharge from the pressure of the fluid within the nozzle, a decrease in the rate of discharge eflecting an increase in the pressure of the fluid within the nozzle,- where'- as an increase in the rate of discharge effects a corresponding decrease in fluid pressure.

As the template l9 and the work piece 14 are rotated by the circular table II the follower 24 will be positioned toward and away from the port 3| in accordance with changes in the configuration of the template. Such positioning of the follower 24 effects changes in the pressure of thefluid within the nozzle 22. These pressure variations are eifective for positioning the work .table 2, to return the follower 24 to the normal distance from .the port 3!. Inasmuch as in the embodiment of my invention illustrated in Figs. 1,2 and 3- the cutter 3 is tationary, as is also the nozzle 22, it follows that if the work table 2 is positioned to maintain a normal distance between the follower 24 and port 3i the work piece l4 will upon completion of the machining operation have a configuration determined by the configuration of the template l9.

Inasmuch as the circular table I! rotates, whereas the work piece may have a shape other than circular, and furthermore may not be con- ?centrically located on the table with respect to the center of rotation thereof, it follows that the periphery of the work piece will n0t be a duplicate The proper contour of the template to give the desired shape to the work piece may be determined, as evident to those skilled in the art, by calculationlor graphically. v

The pattern or template has a shape corresponding to the desired path of movement of the tool to produce the desired finished work piece. By corresponding" is meant that not only is the pattern or template the same shape as the desired work piece, either in greater or smaller proportions thereto; but alsothat the pattern or template is in any desired distorted shape to compensate I for characteristics oi the. machine. A lie the pattern or template must correspond to (the desired work piece, it is not necessarily identical in contour, and, therefore, the term "correpattem or template is purposely designed to result in the desired contour of the work piece to be produced.

Changes in the shape and sizeofthe projection I 25 relative to that of the cutter 2 will also modify a desired shape of the shape of the template ll necessary to, produce the workpiece I4. In some instances the design of the template I! is someport effect corresponding changes in the what simplified by having the projection 25 the struction shown in Fig. 4. As shown, the follower 24 and projection 25 are eliminated. The nozzle 22 is located immediately adjacent the template l9 so that the template the construction and operation will be as described with reference to Fig. 3.

Pressures established within the nozzle 22 are transmitted through a flexible tube 33 to a'relay within a protecting housing33A and shown in cross section in Fig. 5. 1 The tube 33 connects with the interior of a bellows 32 secured to a wall of the housing 33A. The force produced by the fluid pressure acts against the lower or free head of the bellows and is opposed by the inherent resiliency of the bellows and an elliptical spring 35.

The free head of the bellows will therefore assume a position corresponding to the magnitude of the fluid pressure. Movements of the lower head or the bellows position a movable valve member 35A of a hydraulic pilot valve 36 to control the flow of hydraulic fluid to and from a servo-motor 38 having a piston 31 operating the lead screw through a rack 39, spur gears 40, and a final gear 4| which is splined to the lead screw to permit relative axial movement;

Assuming now that the normal distance exists between the port 3| and follower 24 a definite pressure will exist within the bellows 32, wh ch by adjustment of the spring 35 will cause the valve tween the pilot valve 36 and servo-motor 38. If new the follower 24 moves toward the port 3| the pressure within the bellows 32 will increase, causing a downward positioning of the valve member 35A.- a passage of hydraulic fluid between the pilot valve 36 and servo-motor 38 causing the piston 31 to move the work table 2 in a direction to restore the port 3| and follower 24 to normal distance. Upon a decrease in fluid pressure within' the bellows 32 the servo-motor 38 will position the work table 2 in opposite direction, "thereb pos tioning the follower 24 toward the port 2 until normal distance is restored. It 'is apparent that by r per shaping of the template IS the follower 24 may be moved toward and away from t e port 3| as the circular table |1 revolves to effect corresponding movements of the work table 2 relative to the cutter 3 to effect accurate shap-- in of the work piece l4.

Hydraulic fluid, such as oil, used in DOSitlOIilDg the piston 31 of the servo-motor 38 may be pumped by any suitablemeans, such as the oil pump 43 driven by a motor 44. The ump 43 is provided with an inlet pipe 45 extending into an I itself acts as thevalve member for the port 3|. Other than this member 35A to assume a neutral position, i. e. a I position in which no hydraulic fluid passes be-- the outlet pipe 5| with the pump 43 and the outlet port with the exhaust port 48. The movable valve member 36A is provided with sealing glands and 56, which are of substantially the same diameter as the passageway 51 extending longitudinally through the pilot'valve. Oil from the pumpj4-3 is admitted under pressure through pipe 41 to the inlet port which is in the form of an annular chamber. The port 60 is in communication with the passageway 51 through-a plurality of equally spaced upper V- ports 8| and a similar plurality of lower V-ports 62. With the valve member 36A in the neutral position, that is in the position occupied when the follower 24 is the normal distance from the port 3|, then a land 64 restricts communication between V-ports 62 and outlet port 50. Likewise a land 65 restricts communication between v ports 62 and outlet port 5|. When, however, the valve member 36A is'positioned downwardly, for example, the V-ports 6| are partially uncovered so that communication is established between the inlet pipe .1 and the outlet port 50. The area of the uncovered V-ports 6i depends upon the displacement of the valve member 35A from theneutral position. and. accordingly the flow of oil from the inlet pipe i? to the eutlet port 50 will vary depending upon the displacement of the valve member. Conversely upon upward pos tioning of the valve member 33A from theneutral position a portion of the V-ports 62 will be'uncov-- ered, thereby permitting a proportionate flow of pressure fluidp rt 5|.

Also carried by the valve member 33A are lands. 66 and 61 cooperating-with spaced \L-ports 68 and 58 respectively to control the flow of pressure fluid from the outlet port 50 to the exhaust pipe 48. and from the outlet port 5| to the exhaust pipe 49. It will be noted that upon downward positioningof the valve member 36A. which establishes communication between the inlet pipe 41 and outletport 50, communication is likewise established between the outlet port 5| and exhaust .p pe 49. Pressure fluid is thus transmitted through pipe 52 to one side of the piston 31 and simultaneously withdrawn from the opposite iside of the piston through pipe 53 to exhaust port 49. Upward'positioning of the valve member 36A from the neutral position results in op'-.

J posite action, in this instance pressure fluid being iii) oil reservoir 45. and a dischar e nine 41 which is c nnected to the inlet port 65 of the pilot valve 36. Hydraulic fluid returned from t e se vo-v 'from the normal position relative to the port 3|.

transmitted from inlet pipe 41, pipe 53, to one side of piston 31. Pressure fluid is simultaneously withdrawn from the opposite-side of piston 31 through pipe 52 to outlet port 5|], and thenm'tc exhaust pipe 48. It will be noted that whenever the valve member 36A is in other than the neutral position, the piston 31 will continue to move in predetermined direction. Accordingly, upon the follower 24 being in ot er than the normal position. the work table 2, and the work piece M will be pos tioned until normal distarrce is restored. It is further evident that the rate at which the table '2 will be positioned will be dependent upon fthe amount of displacement of the follower 24 If a sudden change in contour of template I! ,occurs, the table 2 will be rapidly po itioned but upon a relatively slow rate of change in the contour of the template a correspondingly slow change n position of the table 2 will occur. Thus the pilot valve 36 will cause the work piece to be accurately positioned relative to the cutter without overshooting or hunting.

Preferably the sealin lands 55 and 56 are of from the inlet pipe 41 to the outlet from the inlet pipe 41 to outlet ports 50 and 5|,

with the member 36A in neutral position because the lands 64 and 65 may be of somewhat less diameter than the passageway, will not aifect the accuracy with which the piston 31 is posi tioned for such pressures will be equal and act in opposite direction on the piston 31. The system Will stabilize with the pilot slightly oil? center to balance total pressures rather than unit pres sures as would be the case with a construction where the piston rod extends through both ends of the cylinder. It will further be noted that the flows into and out of the passageway 51 are radial, so that there is no reaction on the member 36A because of the velocity of flow into and out of the passageway. Furthermore, the pressures are axially balanced due to the equal areas of lands 64, 65, 66 and 61 so that no reaction exists due to the resultant of the oil pressures acting in an upward or downward direction.-

While in general I have found it preferable to operate the table 2 or comparable device indirectly from the fluid pressures established within the nozzle 22 by means of a hydraulic relay, in some instances where a relatively light machining operation is being performed, or an extreme degree of accuracy is not required, I have found it possible to dispense. with the hydraulic relay system and employ in its stead a pneumatic relay system as shown in Fig. 6.

Therein I show fluid pressure, such as compressed air, transmitted from the pipe 28 ahead of the orifice 30 to a pilot valve 18 by a pipe 1!. The pilot shown in cross-section may be so constructed that downward positioning of the movable valve member 12 permits pressure fluid to be transmitted to one side of the piston 81 and simultaneously exhausts pressure fluid from the opposite side of the piston 31. Conversely upon upward positioning of the member 12 reverse operation of the piston 31 will occur. Whenthe normal distance exists betweenport 3| and template IS the member 12 is positioned so that the lands. thereon are adjacent theoutlet ports leading tothe servo-motor 88.

In the embodiments of myinvention so far described the work piece has been moved,'whereas the cutter or tool has remained stationary. In Figs. 7 and 8 I disclose a further embodiment of my invention in conjunction'with an engine lathe wherein the work piece remains in fixed position and the tool, or cutter, is moved. It will be evident to those skilled in the art however that in all of the embodiments it is the relative movement between the work piece and the tool which is of importance and which is controlled by my invention.

Referring to Figs. 7 and 8 I therein .show a typical engine lathe having a bed 88, rotatable face plate 8!, andrtail stock 82. It is further provided with a, carriage 83 movable on guideways 84, 85 longitudinally alongthe bed 88.. Nor.-

mally the longitudinalmovement of the carriage is controlled by a feedscrew 8|, which may be driven by any suitable source of power (not shown) at any desired speed by means of suitable reducing gears (not shown).

' Mounted on the carriage I8 is a cross-slide 81 carrying a tool holder and tool 81A which by way of example I have shown as forming a work piece 88 into general irregular conical form. In the embodiment of my invention shown the transverse motion of the cross-slide 81 is automatically controlled so that the work piece 88 is formed to correspond in shape to a template 89, which is secured to the bed 88 of the lathe by suitable clamping means 90.

The system for positioning the tool 81A. relative to the, work piece 88 is substantially the same as that described for positioning the cutter 3 relative to the work piece l4. Nozzle 22 is resiliently mounted inan arm 9| secured to the cross-slide 81. The projection 25 of the follower 24 bears against the edge of the template 89, which has a contour to which the work piece 88 is to be shaped. Pressures established in the nozzle 22 are transmitted to the relay 33A, which'in turn acts to control the positioning of the piston 3'! in servo-motor 38. Positioning of the piston 81 controls the transverse positioning of the tool 81 through a rack 39 and suitable gears 92A.

In order that the servo-motor 38, relay 33A and associated apparatus may move with the cross-slide 81 longitudinally along the lathe they are shown mounted on a truck 92 provided with flanged wheels 93 riding on rails 94. The truck 82 is secured to the carriage 83 so that the servomotor is maintained at proper operating distance from the cross-slide 81.

In operation, as. the template 89 changes in shape corresponding variations in pressure within the nozzle 22 occur, which effect transverse operation of the cross-slide 81 to maintain the follower 24 at normal distance from the port 8|. Simultaneously, the tool 81 is moved transversely so that the work piece 88 assumes the same shape as the template 89. The cross-slide 81 is moved v48, longitudinally by the feed screw 86 and carriage 83 at desired speed by any suitable source of power as heretofore described.

In the embodiments of my invention illustrated I have shown the lead screw of a machine tool operated by a servo-motor comprising a piston and a cylinder. It is evident that other types or servo motors may be used such, for example, as hydraulic motors and the like. Because of the positive 'action and relative simplicity of a piston and cylinder type of servo-motor I find it preferable to use in most instances. The sole disadvantage of this type of servo-motor in the past has been that in those instances where materially great changes in the contour of the template ocour, in order to provide corresponding movements of the work piece relative to the tool ,a cylinder and rack of too great length to be practical was required. I have devised a system, however, whereby a cylinder and rack of desired length may be used regardless of the configuration of the template. Because the novelty of my system does not reside in any particular element, but in the novel cooperation between a combination of elements, I have chosen to illustrate the system schematically.

Referring to Fig. 9, I therein show the nozzle 22 and cooperating template l9. It will be evident that if the template l8 has large changes in configuration in order to obtain corresponding changes in. relative positions of the work piece and tool, it will be necessary that the lead screw l IA be revolved an exceptionally large number of turns, which ordinarily would require rack 88 and cylinder 88 to be impractically long. In

accordance with my invention, however, I employ a rack and cylinder of desired length and when the rack is near the end oi its travel in either direction I declutch the lead screw HA from the gear A by means of an electromagnetically operated clutch I00, and simultaneously stop the machine. I then, by means of a high speed reset mechanism, position the piston 31 to or about its mid position. Next, I throw in the Describing first the operation whereby the lead screw IIA is declutched from the gear 4IA when the rack 39 approaches the end of its travel in one direction, a contact IOI carried by the rack 39 engages a stationary contact I02, thus closing the circuit for the coil I03 of a solenoid I04. The solenoid has a movable armature I05 which is positioned downwardly from its mid or neutral position by energization of the coil I03.

The armature I05 carries a horizontal extension I06 terminating in a contact I01 normally, that is when the coil I03 is not excited, engaging a stationary contact I08. The clutch I has a coil I09 which holds the clutch in so that movements of the rack 39 are transmitted to the lead screw IIA. When the coil I09 is deenergized, the clutch I00 is declutched so that regardless of movement of the rack 39, the lead screw IIA re-. mains stationary. As shown, energization of the coil I09 is controlled by contacts I0I-IOB. Thus, upon energization the coil I03 and the armature Imoving downwardly clutch I00 is opened so that thereafter until contacts I0'Il 08 again engage, the lead screw IIA will remain stationary.

So far as the operation of the clutch I00 is concerned, the same sequence of events occurs upon the rack '39 approaching the end of its travel in opposite direction. In this'instance the stationdisplaced from the neutral .position thereby per mitting hydraulic fluid to be transmitted to one of the pipes H6 or III and withdrawn from the other pipe.

In operation upon the contact IOI engaging stationary contact I02, for example, indicating that the rack 39 has reached its approximate travel and in that direction, the armature I05 will move downwardly, thereby connecting inlet port II9 with pipe I ll so that hydraulic fluid will be transmitted to the cylinder 39 and position piston 31 to the right as shown in the drawings so that the rack is restored to a position within its operating range. Simultaneously, with the transmittal of hydraulic fluid to pipe I ll, hydraulic fluid will be withdrawn from the opposite side of piston 31 through pipes 52, H6 and exhaust port I20. The operation when the contact IIO engages the stationary contact I02 is similar in this instance to the armature I05 moving upwardly thereby connecting inlet port II9 with pipe II6 so that hydraulic fluid is transmitted to pipe 52 and positioning the rack 39 in opposite direction. Simultaneously, pipe I I1 is connected with exhaust port I2I so that hydraulic fluid is withdrawn from pipe 53 and the opposite side of piston 31.

To prevent the armature I05 bein restored to the neutral position as soon as disengagement between contact I02 and contact IM or H0 occurs and, further, to govern the resetting of rack 39, I provide a time delay means, in the drawings ary contact I02 engaging a contact IIO secured to the rack 39 and effecting upward movement of the solenoid I04 due to energization of a coil III. It will be noted that in this case contacts I0I-I08 will disengage, thereby deenergizing coil I09 and declutching rack 39 from the lead screw HA.

The lower end of the armature I05 forms a movable valve member 2 of a pilot valve II3. Carried by the member IIZ are lands I I I and I I5 normally disposed in a closed position so that hydraulic fluid is neither transmitted to or from pipes H9 and III. The pilot valve is supplied with oil under pressure from any suitable source (not shown) throughan inlet port H9 disposed between lands IM and I I5. The pilot valve also has two exhaust ports I20 and I2I.

Pipe III leads to pipe 53 connected to the cylinder 36 on one side of piston 31. Pipe I I6 is connected to pipe 52, which is connected to cylinder I pipes H6 and Ill. Upon either upward or down ward movement of the armature I05 it will be observed; however, that lands II and H5 will be shown as a dash pot I22, which may be provided with an adjustable bleed valve I23 to govern the time required for the armature I05 to be repositloned'to the neutral position and hence the position to which the piston 3'5 will be restored after having reached an extreme of travel. Conveniently, the dash pot I22 may be provided with biasing springs I25 to maintain the armature I05 in'neutral position during periods of normal operation.

As will-be understood by those familiar with the art, I may by proper design of pilot I I3 render the relay 33A substantially inoperative during the period of time when the armature I05 is displaced from the mid or neutral position. Thus, I may provide for much greater flows at higher pressures through the pilot I I3 so that the operation of the relay 33A has an unappreciable effect upon ing periods when the piston 31 is being reset. By I way of diagrammatic illustration, I show in pipes 52 and 53 solenoid operated valves I26 and I2I normally energized and in open position so that hydraulic fluid is transmitted freely from the relay 33A to the cylinder 39. The energization of the solenoids I26 and I2! is controlled by a relay I29, the energization of. which in turn is controlled by contacts I0l-I03. Thus as long as contacts I0II08 are closed, the solenoids I26 and I2! are energized. When, however, the armature I05 is displaced from the neutral position,. solenoid relay I29 breaks the circuit through solenoid valves I26--I2l so that communication between relay 33A and cylinder 38 is stopped. Normal communication will be reestablished when the armature I05 is returned to the neutral position and contacts I0I-l08 reengage. Thus. if preferable. I may'during a reset operation isolate the cylinder 36 so that the piston 31 is controlled solely from pilot H3.

During the reset operation. the machine is pro!- erably stopped to prevent the tool from incor I81] controls the rectly forming the work piece while the clutch I is disengaged. To this end I show the motor I3A, driving the machine, as controlled from contacts I01I08. Connected in the motor circuit is a solenoid relay I30 normally energized through contacts I01--I08. When these contacts disengage, however, solenoid I30 breaks the circuit to altered during the period of time when the reset operation is taking place.

In Fig. 10, I show a modified form of'my invention applied to an engine lathe I50 similar to the lathe illustrated in Figs.- 7 and 8. In Fig. 11 the control and operating circuits for the embodiment of my inventionillustrated in Fig. 10 are shown diagrammatically.

Referring to Figs. 10 and 11 the carriage I-I is arranged to be positioned longitudinally along the lathe I50 by a servo-motor I52 having a piston rod I53 operatively connected to the carriage. A cross-slide I54 mounted on the carriage I5| is positioned transversely by means of a similar servo-motor I55 secured to and movable with the carriage I5I. In the embodiment of my invention illustrated inFig. the tool I54A carried by the cross-slide I54 is positioned to form a work piece I56 to conform with the shape of a pattern or template I51. As the carriage I5I is positioned along the lathe by the servo-motor I52 transverse change in the profile of the pattern I51 eflect corresponding changes in the relative positions or a pivoted follower or feeler I58 and nozzle I 59 The nozzle I59 is supplied with fluid under. pressure, such as compressed air, from a source (not shown),

through a shut-oi! valve I50, a reducing valve I80A, a stabilizing volume tank I5I and a suitable resistance such as an oriflce I62. As in the embodiments of my invention previously described, compressed air is continuously discharged through the nozzle I59 to the atmosphere and changes in the position of the i'eeler I58 relative to the nozzle I59 cause changes in the pressure within the pipe I53 connecting the nozzle I59 to the oriflce I52. Variations in pressure within the pipe I69 are transmitted through a pipe I54 to an expansible contractible chamber suchas a bellows I65 positioning the movable valve member I55 of a flow or hydraulicfluid to and from a servo-motor I 55.

when the proflle of the pattern I51 i parallel to the line, of travel of the carriage I5I a certain distance will exist between the nozzle crease in pressure will cause the servo-motor I55 to position the cross-slide I55 so that the nozzle I59 carried thereby moves away from the feeler I58 until normal distance is restored therebetween. The tool I54A also carried by the crossslide I55 will be moved relative to the work piece I56 a corresponding amount, and hence the lat- I produced by the fluid pressure within the bellows I65 is opposed by a coil spring IN to which it is connected by means of a stirrup I12. The efiective length of the spring I1I may be varied by means of an adjustment I13, so that the displacement of the movable valve member I66 from the neutral position for a change in pressure within the bellows I65 of given amount may be varied. As the speed with which the piston I55A of the servo-motor I55 is positioned depends upon the displacement of the movable valve member I66 from the neutral position, it is evident that the adjustment I13 provide a means for varying'the speed with which the tool I54A is pos.tioned relative to the work piece I56 for a given change in the relative positions of the feeler I58 and nozzle I59.

In Figs. 15 and 16 I show further forms of spring and bellows arrangements which may be used in place of the construction shown in Figs.

12 and 13. Referring to Fig. 15, I therein show a bell crank 315 pivotally mounted on a support port 316 by a thumb screw 311. Secured to the bell crank 315 is a leaf spring 318 to which is secured at its free end the stirrup I12.

ported by the bell crank 315 and adjustable therepilot valve I61. The pilot valve I59 and feeler I55. When this distance, which for convenience I call the exists a sumcient pressure is maintained within the bellows I65 to hold the movable valve member I66 in a neutral position so that hydraulic fluid is transmitted neither to nor .i'rom the servomotor I and the cross-slide I54 remains stationary relative to the carriage I5I. Assuming, however. by way of example that the feeler I58 moves toward the nozzle I59, the pressure within the pipe I63 and that transmitted to the bellows I65 will increase proportionately. Such innormal distance, 6

- those familiar with the art.

.the pilot valve member I66 along by a thumb screw 318A is a movable fulcrum 319 having a clamping means 319A for islarying the effective length of the leaf spring Thumb screw 311 afiords a means for adjusting the vertical position of movable valve member I66 so that for the pressure existing within bellows I65 whenfeeler I58 is at the normal distance from nozzle I59 no fluid will pass from the hydraulic pump I68 to servo-motor I55, and the tool I54A will be locked in a stationary position relative to the carriage I5I. A change in position of the fulcrum 319 varies the rate of transverse movement of tool I54A for a given movement 01 .reeler I58 toward or away from the nozzle I59.

Referring to Fig. 16 I show the force produced by fluid pressure within the bellows I65 opposed by an elliptical spring 380 so that movement of will be proportional to variations in pressure-therein. "In the construction shown in Fig. 16 the spring 380 is preferably located within the housing I10.

The housing I10 may be mounted, as shown in Fig. 10, directly on the servo-motor I55. This construction provides a compact power unit which may be readily adapted as an attachment to any. machine tool, as will be appreciated by It is evident, however, that the housing I10 and parts supported thereby may. if desired, be located a considerable distance from the servo-motor I55.

Sup-

in Fig. 12-1 have illustrated a centrifugal pump I68 driven by an electric motor I68. Oil is drawn into the pump I68 from the reservoir formed by the housing I through an inlet I14 and is transmitted to the pilot valve I61 through a connection I15. In order that the oil'transmitted to the pilot I61 may be main-- tained at substantially constant pressure a connection I16 is provided in which'is located a relief valve I11, which may be adjusted for any desired pressure.

In Fig. 14 I show an alternate form of pump construction which may be used in place of the pump I68. The pump I18 shown in Fig. 14 is particularly adapted to the pumping of small volumes of fluid and has the advantage that only "a volume of fluid necessary to maintain the pressure desired is actually pumped, thereby decreasing the power consumption and wear on the moving parts.

Referring to Fig. 14, the pump I18 comprises a housing-119 forming a cylinder inwhich is disposed a piston I80 having an extension IBOA forming a yoke guided in-ways I19A. Oil or other fluid to be pumped is drawn into the cyland dischargedinder through an inlet I8I through an outlet I82. Cyclically the piston I80 is moved upwardly so that its lower end rises above the inlet I8I, by a cam member I83 continuously rotated by any suitable motor means (not shown).

The piston I80 in moving upwardly creates a suction in the cylinder so that upon the inlet I8I being uncovered oil is drawn into the cylinder. The cam I83 is designed'so that upon the piston I80 being lifted to the extreme of its upward travel it is released and urged downwardly solely by a spring I84. Acting against the force produced by the spring I84 is the pressure of the oil in the outlet I82, so that the downward travel of the piston will be limited to that necessary to maintain the pressure of the oil in the outlet I82 at the desired value. It is, therefore, evident that the stroke of the piston I80 will vary as required to maintain the oil pressure in the outlet I82 at the desired value.

valve member I66 hydraulic fluid is admitted to servo-motor I55 on one side of-piston I55A and discharged from the other side. Conversely, upward positioning of the movable valve member I66 opens outlet port 363 to inlet port 36I, and simultaneously opens outlet port 362 to exhaust port 364. Thus downward positioning of the movable valve member I66 from the neutral position effects operation of piston I55A in one direction, whereas'upward ositioning efiects operwhich acts bearing member if positioned upwardly there- Disposed in the outlet I82 is a check valve I85 to prevent reverse flow of fluid during the suction stroke of the piston I80. It will be evident that a similar check valve may be provided in the inlet I 8| to prevent oil being discharged through the inlet during the pressure or compression stroke. However, as illustrated, I prefer to so locate the inlet port I8I that it is uncovered only when the piston I80 is substantially at its upward extreme of travel so that the piston I80 itself in eflect forms a check valve and prevents the discharge of oil through the inlet I8I during its pressure or compression stroke.

The piston I80 is provided with a plurality of circumferential grooves I86 which act to prevent the leakage of oil and also act to prevent undue lateral thrust of the pistonv against the cylinder.

wall due to seepage of oil along one side thereof. In Fig. 1'1 I show the pilot valve I61 in cross section and to larger size. A body member 350 has a cylindrical bore in which are disposed sleeves 35I, 352 and bearing members 353, 354. Caps 355 and 356 screwed to the body 350 hold the sleeves and bearing members in position. The movable valve member I66, positioned by bellows I65, is provided with lands 351, 358, 358 and 360 of slightly less diameter than the bore in sleeves 35I, 352. Lands 358, 350 control the ation of piston I55A in the opposite direction.

Sleeve 35I which is identical with sleeve 352 is shown to larger size in Fig. 18. The inlet port 36I consists of a slot 366, whereas the outlet port consists of a plurality of circumferentially spaced holes 361. The waste port is similar to the inlet port 366 and comprises a slot 368. The sleeve is also provided with spaced collars 369, 310 serving to properly align the sleeve in the housing 350 and acting to separate the inlet port from the outlet port and the outlet port from the waste port.

In Fig. 19 I show an end view of the bearing member 353, the bearing member 354 being identical therewith. As shown, the end of bearing member 353 adjacent the sleeve 35I is conically recessed and provided with a radial slot 31I to prevent land '351 adhering to the against.

The pilot valve I61 is inherently stable as a displacement of the valve member I66 from neutral position with consequent flow of hydraulic fluid produces a slight reaction tending to return the movable valve member to the neutral position. That such reaction exists will be evident from an'inspection of the construction shown in Fig. 17 for upon a displacement of the member I66 from neutral position the sole unbalancedforce is that in the waste port 364 or 365. This stabilizing reaction may be brought to any value desired by proper design of the waste .ports. Also by having the valve member I66 journaled in bearing members 353, 354 it is possible to have the lands 351, 358, 359 and 360 of slightly less diameter than the bore through sleeves 35I and 352, thereby reducing- 2;.friction to inimum. Further, to reduce friction the sect movable valve member I66, journaled in bearing members 353 and 354, are provided with a plurality of grooves 312, thereby preventing pressure building up on one side of the-valve member and producing lateral thrust. Such grooves also reduce the leakage which otherwise would exist between the interior and exterior of the pilot valve.

In' mechanisms of the type described, it is de.

sirable to modify the rate of relative movement of tool and work piece in one direction whenever a relative movement of the tool and work piece in a second direction is required. Thus in the embodiment of my invention illustrated in Figs. 10 and 11 upon any change in shape of the pattern I51 requiring a transverse movement of the 

